Aircraft electric motor

ABSTRACT

Aircraft electric motors are described. The electric motors include an annular rotor sleeve having an inner wall, a connecting wall, and an outer wall, wherein the inner wall, the connecting wall, and the outer wall define a U-shaped channel configured to receive a U-shaped magnet structure and a sleeve inner cavity defined radially inward from the inner wall, a hub connector extending radially inward from the inner wall into the sleeve inner cavity, a hub arranged in the sleeve inner cavity and fixedly connected to the hub connector, wherein the hub is configured to rotate with rotation of the rotor sleeve, and a U-shaped magnet structure arranged within the U-shaped channel of the rotor sleeve. At least one of the rotor sleeve, the hub connector, and the hub are formed from a composite material.

BACKGROUND

The present disclosure relates to electric motors, and moreparticularly, to electric motor assemblies with high efficiency andpower density with a light weight for aircraft applications.

Traditional electric motors may include a stator and a rotor, withelectrical motor windings in the stator that, when energized, driverotation of the rotor about a central axis. Heat is generated in themotor windings, which are located in slots in the stator. The windingsare separated from the exterior of the motor by layers of insulation andlaminated steel, which makes up the stator. These contributors tointernal thermal resistance limit the allowable heat generation and thusthe allowable electrical current in the windings. The energy density ofan electric motor is typically limited by heat dissipation from themotor windings of the stator. The requirement to be met is a maximum hotspot temperature in the motor windings that is not to be exceeded.Conventional motor thermal management includes natural convection fromlarge fins on the outside of a motor jacket, or liquid cooling in themotor jacket. Both of these solutions undesirably add volume and/orweight to the motor, due to the addition of, at least, the jacket.

BRIEF DESCRIPTION

According to some embodiments of the present disclosure, aircraftelectric motors are provided. The aircraft electric motors include anannular rotor sleeve having an inner wall, a connecting wall, and anouter wall, wherein the inner wall, the connecting wall, and the outerwall define a U-shaped channel configured to receive a U-shaped magnetstructure and a sleeve inner cavity defined radially inward from theinner wall, a hub connector extending radially inward from the innerwall into the sleeve inner cavity, a hub arranged in the sleeve innercavity and fixedly connected to the hub connector, wherein the hub isconfigured to rotate with rotation of the rotor sleeve, and a U-shapedmagnet structure arranged within the U-shaped channel of the rotorsleeve. At least one of the rotor sleeve, the hub connector, and the hubare formed from a composite material.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the hub comprises a plurality of spokes extending betweenan inner element and an outer element of the hub.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude an outer sleeve arranged about an exterior of the outer wall ofthe rotor sleeve.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude a cooling system having a heat exchanger arranged radiallyoutward from the outer wall of the rotor sleeve.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the composite material is at least one carbon fiber fabric,carbon fiber composite, and braided material.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the rotor sleeve is formed of two pieces that are joinedtogether, wherein each piece of the rotor sleeve is substantiallyJ-shaped.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the rotor sleeve is formed of two pieces that are joinedtogether, wherein one piece of the rotor sleeve is substantiallyJ-shaped and the other piece of the rotor sleeve is substantiallyl-shaped.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the rotor sleeve is formed of two pieces that are joinedtogether, wherein one piece of the rotor sleeve is formed from metal andthe other piece of the rotor sleeve is formed from the compositematerial.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude an inner sleeve arranged within the U-shaped channel andconfigured to provide support to the U-shaped magnet structure.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude a stator arranged within the U-shaped magnet structure.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude an input shaft connected to the hub.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude a gear assembly arranged within the sleeve inner cavity.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the rotor sleeve is operably connected to the gear assemblyby the hub.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the gear assembly comprises a sun gear, one or moreplanetary gears, and a ring gear.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that an input shaft connects the hub to the sun gear and anoutput shaft is operably connected to the ring gear.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude a motor housing, wherein the rotor sleeve is arranged within themotor housing.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the motor housing is substantially annular in shape, havingan outer wall and an inner wall, wherein a rotor-stator cavity isdefined between the outer wall and the inner wall, and the rotor sleeveis arranged within the rotor-stator cavity.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the motor housing is substantially annular in shape, havingan outer wall and an inner wall, wherein a gear assembly cavity isdefined radially inward from the inner wall, and a gear assembly isarranged within the gear assembly cavity.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the motor housing includes gear shafts within the gearassembly cavity, the gear shafts configured to support gears of the gearassembly.

In addition to one or more of the features described herein, or as analternative, further embodiments of the aircraft electric motors mayinclude that the hub comprises a plurality of spokes extending betweenan inner element and an outer element of the hub.

The foregoing features and elements may be executed or utilized invarious combinations without exclusivity, unless expressly indicatedotherwise. These features and elements as well as the operation thereofwill become more apparent in light of the following description and theaccompanying drawings. It should be understood, however, that thefollowing description and drawings are intended to be illustrative andexplanatory in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art fromthe following detailed description of the disclosed non-limitingembodiments. The drawings that accompany the detailed description can bebriefly described as follows:

FIG. 1A is a partial view of an embodiment of electric motor;

FIG. 1B is a cross-sectional view of an embodiment of a stator core ofthe electric motor of FIG. 1A;

FIG. 2A is a schematic illustration of an aircraft electric motor inaccordance with an embodiment of the present disclosure;

FIG. 2B is a side elevation view of the aircraft electric motor of FIG.2A;

FIG. 2C is a partial cut-away illustration of the aircraft electricmotor of FIG. 2A;

FIG. 2D is a separated-component illustration of the aircraft electricmotor of FIG. 2A;

FIG. 3A is a schematic illustration of a rotor and stator of an aircraftelectric motor in accordance with an embodiment of the presentdisclosure;

FIG. 3B is a schematic illustration of the rotor and stator of FIG. 3Aas arranged within a rotor sleeve in accordance with an embodiment ofthe present disclosure;

FIG. 4 is a schematic illustration of a rotor sleeve in accordance withan embodiment of the present disclosure;

FIG. 5A is a set of different configurations of a rotor sleeve inaccordance with an embodiment of the present disclosure;

FIG. 5B is a set of different configurations of a rotor sleeve inaccordance with an embodiment of the present disclosure;

FIG. 6A is a schematic illustration of a rotor sleeve and hub inaccordance with an embodiment of the present disclosure;

FIG. 6B illustrates an alternative configuration of a hub in accordancewith an embodiment of the present disclosure;

FIG. 7A is a schematic illustration of an aircraft electric motor inaccordance with an embodiment of the present disclosure;

FIG. 7B is an alternative view of the aircraft electric motor of FIG.7A;

FIG. 7C is a front elevation cross-sectional view of the aircraftelectric motor of FIG. 7A as viewed along the line C-C shown in FIG. 7B;

FIG. 7D is a schematic illustration of a gear assembly of the aircraftelectric motor of FIG. 7A;

FIG. 7E is an alternative view of the gear assembly of the aircraftelectric motor of FIG. 7A;

FIG. 8 is a schematic illustration of a motor housing of an aircraftelectric motor in accordance with an embodiment of the presentdisclosure; and

FIG. 9 is a schematic view of a power system of an aircraft that mayemploy embodiments of the present disclosure.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, that the followingdescription and drawings are intended to be illustrative and explanatoryin nature and non-limiting.

DETAILED DESCRIPTION

Referring to FIGS. 1A-1B, schematic illustrations of an electric motor100 that may incorporate embodiments of the present disclosure areshown. FIG. 1A illustrates a cross-sectional view of the electric motor100 and FIG. 1B illustrates a cross-sectional view of a stator core ofthe electric motor 100. The electric motor 100 includes a rotor 102configured to rotate about a rotation axis 104. A stator 106 is locatedradially outboard of the rotor 102 relative to the rotation axis 104,with a radial air gap 108 located between the rotor 102 and the stator106. As illustrated, the rotor 102 may be mounted on a shaft 110 whichmay impart rotational movement to the rotor 102 or may be driven byrotation of the rotor 102, as will be appreciated by those of skill inthe art. The rotor 102 and the shaft 110 may be fixed together such thatthe rotor 102 and the shaft 110 rotate about the rotation axis 104together as one piece.

The stator 106 includes a stator core 112 in which a plurality ofelectrically conductive stator windings 114 are disposed. In someembodiments, such as shown in FIG. 1A, the stator core 112 is formedfrom a plurality of axially stacked laminations 116, which are stackedalong the rotation axis 104. In some embodiments, the laminations 116are formed from a steel material, but one skilled in the art willreadily appreciate that other materials may be utilized. The statorwindings 114, as shown, include core segments 118 extending through thestator core 112 and end turn segments 120 extending from each axialstator end 122 of the stator core 112 and connecting circumferentiallyadjacent core segments 118. When the stator windings 114 are energizedvia an electrical current therethrough, the resulting field drivesrotation of the rotor 102 about the rotation axis 104. Although FIG. 1Aillustrates the stator core 112 arranged radially inward from the statorwindings 114, it will be appreciated that other configurations arepossible without departing from the scope of the present disclosure. Forexample, in some embodiments, the stator structure may be arrangedradially inward from a rotating rotor structure.

FIG. 1B is an axial cross-sectional view of the stator core 112. Eachlamination 116 of the stator core 112 includes a radially outer rim 124with a plurality of stator teeth 126 extending radially inwardly fromthe outer rim 124 toward the rotation axis 104. Each of the stator teeth126 terminate at a tooth tip 128, which, together with a rotor outersurface 130 (shown in FIG. 1A) of the rotor 102, may define the radialair gap 108. Circumferentially adjacent stator teeth 126 define anaxially-extending tooth gap 132 therebetween. Further, in someembodiments, a plurality of stator fins 134 extend radially outwardlyfrom the outer rim 124.

Electric motors, as shown in FIGS. 1A-1B may require cooling due to highdensity configurations, various operational parameters, or for otherreasons. For example, high-power-density aviation-class electric motorsand drives may require advanced cooling technologies to ensure properoperation of the motors/drives. These machines are generally thermallylimited at high power ratings and their performance can be improved bymitigating thermal limitations. To maintain desired temperatures, athermal management system (TMS) is integrated into the system, whichprovides cooling to components of the system.

Onboard an aircraft, power requirements, and thus thermal managementsystem (TMS) loads, are substantially higher during takeoff. Sizing ofthe TMS for takeoff conditions (i.e., maximum loads) results in a TMShaving a high weight to accommodate such loads. This results in greaterweight and lower power density during cruise conditions which do notgenerate such loads, and thus does not require a high cooling capacityTMS. Balancing weight constraints and thermal load capacities isimportant for such aviation applications.

In view of such considerations, improved aviation electric motors areprovided herein. The aviation electric motors or aircraft electricmotors, described herein, incorporate lightweight materials and compactdesign to reduce weight, improve thermal efficiencies, improve powerefficiencies, and improve power density.

Turning now to FIGS. 2A-2D, schematic illustrations of an aircraftelectric motor 200 in accordance with an embodiment of the presentdisclosure are shown. FIG. 2A is an isometric illustration of theaircraft electric motor 200, FIG. 2B is a side elevation view of theaircraft electric motor 200, FIG. 2C is a partial cut-away viewillustrating internal components of the aircraft electric motor 200, andFIG. 2D is a schematic illustration of components of the aircraftelectric motor 200 as separated from each other. The aircraft electricmotor 200 includes a motor housing 202, a cooling system 204, a firstpower module system 206, and a second power module system 208.

The motor housing 202 houses a stator 210 and a rotor 212, with therotor 212 configured to be rotatable about the stator 210. In thisillustrative embodiment, the rotor 212 includes a U-shaped magnet 214arranged within a similarly shaped U-shaped rotor sleeve 216. The rotorsleeve 216 is operably connected to a hub 218. The hub 218 is fixedlyattached to a first shaft 220. The first shaft 220 is operably connectedto a second shaft 222. In some configurations, the first shaft 220 maybe a high speed shaft and may be referred to as an input shaft. In suchconfigurations, the second shaft 222 may be a low speed shaft and may bereferred to as an output shaft. The connection between the first shaft220 and the second shaft 222 may be by a gear assembly 224, as describedherein.

The cooling system 204 is configured to provide cooling to thecomponents of the aircraft electric motor 200. The cooling system 204,as shown in FIG. 2D, includes a heat exchanger 226 and a header 228. Theheat exchanger 226 and the header 228 may form a closed-loop coolingsystem that may provide air-cooling to a working fluid at the heatexchanger 226. The header 228 may be, in some configurations, atwo-phase di-electric cooling header. A cooled working fluid may bepumped from the heat exchanger 226 into the header 228 using a pump 229and distributed into embedded cooling channels 230 that are arrangedwithin the stator 210. As the aircraft electric motor 200 is operated,heat is generated and picked up by the working fluid within the embeddedcooling channels 230. This heated working fluid is then passed throughthe header 228 back to the heat exchanger 226 to be cooled, such as byair cooling. Although described as air-cooling, other cooling processesmay be employed without departing from the scope of the presentdisclosure.

As shown, the heat exchanger 226 of the cooling system 204 may be acircular structure that is arranged about the motor housing 202. Thisconfiguration and arrangement allows for improved compactness of thesystem, which may be advantageous for aircraft applications. The rotorsleeve 216 with the magnets 214, the stator 210, and the gear assembly224 fit together (although moveable relative to each other) within themotor housing 202, providing for a compact (low volume/size) design.

As noted above, the rotor sleeve 216 may be operably coupled to a firstshaft 220 by the hub 218. The first shaft 220 may be operably coupled toa first gear element 232 and the second shaft 222 may be operablycoupled to a second gear element 234. The first and second gear elements232, 234 may form the gear assembly 224. The first and second gearelements 232, 234 are arranged to transfer rotational movement from thefirst shaft 220, which is driven in rotation by the hub 218 and therotor sleeve 216 of the rotor 212, to the second shaft 222. In someembodiments, the first shaft 220 may be operably connected to a sun gearas the first gear element 232 that engages with a plurality of planetarygears and drives rotation of the second gear element 234 which may beoperably connected to the second shaft 222. In some embodiments, thesecond shaft 222 may be connected to a fan or other component to berotated by the aircraft electric motor 200.

The aircraft electric motor 200 includes the first power module system206 and the second power module system 208. The first and second powermodule systems 206, 208 can include capacitors and other electronics,including, but not limited to, printed circuit boards (PCBs) that mayenable control and operation of the aircraft electric motor 200. Again,the profile of the aircraft electric motor 200 of the present disclosurepresents a low profile or compact arrangement that reduces the volume ofthe entire power system, which in turn can provide for improved weightreductions. In some embodiments, the first and second power modulesystems 206, 208 may be electrically connected to the stator 210 tocause an electric current therein. As the electric current will inducean electromagnetic field which will cause the rotor 212 to rotate.

Referring now to FIGS. 3A-3B, schematic illustrations of a portion of anaircraft electric motor 300 in accordance with an embodiment of thepresent disclosure is shown. FIGS. 3A-3B illustrate a portion of a rotor302 and a stator 304 of the aircraft electric motor 300. FIG. 3Aillustrates the rotor 302 and the stator 304 and FIG. 3B illustratesthese components arranged within a rotor sleeve 306.

The rotor 302 is formed of a plurality of U-shaped magnets 308. In someconfigurations, the plurality of magnets 308 can be arranged withalternating polarity in a circular structure. Arranged within the “U” ofthe U-shaped magnets 308 is the stator 304. The stator 304 is formed ofa plurality of windings 310. In this configuration, the windings 310 arearranged with a header 312. The header 312 may be part of a coolingsystem, such as that shown and described above. The header 312 can beconfigured to cycle a working fluid through cooling channels 314 forcooling of the windings 310, as shown in FIG. 3B.

The windings 310 may be wrapped about a support structure 316. Thesupport structure 316, in some embodiments and as shown in FIG. 3B, mayinclude a laminate portion 318 and a magnetic portion 320. In some suchembodiments, the laminate portion 318 may be formed from cobalt steellaminate and the magnetic portion 320 may be formed from a soft magneticcomposite. The laminate portion 318 may be provided to capture in-planeflux from outer and inner rotor. The magnetic portion 320 may beprovided to capture end rotor flux and may take a shape/filler in a gapthrough the end turns of the coil. The windings 308 include endconnections 322 and may be electrically connected to one or more powermodule systems of the aircraft electric motor, such as shown above.

As shown in FIG. 3B, the magnets 306 are U-shaped and arranged withinthe rotor sleeve 306. The rotor sleeve 306 is a substantially U-shapedsleeve that is sized and shaped to receive the U-shaped magnets 308. Inthis illustrative configuration, the rotor sleeve 306 can include aninner sleeve 324. The inner sleeve 324 may be configured to providesupport to a portion of the magnets 308. It will be appreciated thatthere is no direct contact between the windings 310 and the magnets 308.This lack of contact enables free rotation of the rotor 302 relative tothe stator 304 during operation.

Turning now to FIG. 4 , a schematic illustration of a rotor sleeve 400in accordance with an embodiment of the present disclosure is shown. Therotor sleeve 400 may be configured to house a U-shaped magnet structureof a rotor for an aircraft electric motor in accordance with the presentdisclosure. As shown, the rotor sleeve 400 is an annular structure orring-shaped structure, allowing for components to be installed withinthe structure of the sleeve, and within the central bore or through holeof the annular structure. The rotor sleeve 400 includes an innerdiameter wall 402, a connecting wall 404, and an outer diameter wall406. The inner diameter wall 402, the connecting wall 404, and the outerdiameter wall 406 define a U-shaped channel 408 for receiving a U-shapedmagnet structure, as described above. The inner diameter wall 402 alsodefines a sleeve inner cavity 410. The sleeve inner cavity 410 is sizedand shaped to receive a gear assembly such as that shown and describedherein. The sleeve inner cavity 410 enables a compact configuration withthe gearing of the aircraft electric motor being housed and arrangedwithin (radially inward from) the rotor and stator of the motor.

Extending radially inward from at least one of the inner diameter wall402 and the connecting wall 404 is a hub connector 412. The hubconnector 412 allows for connection and attachment to a hub, which inturn can be operably connected to one or more shafts and the gearassembly arranged within the sleeve inner cavity 410, as shown anddescribed herein.

The rotor sleeve 400, in accordance with some embodiments, may be formedwith a compounded curvature. In some embodiments, the material of therotor sleeve 400 may be formed from a highly drapeable composite sheetmaterial, such as, carbon fiber fabrics, carbon fiber composites, and/orbraided materials. In other embodiments, the rotor sleeve 400 may beformed from metal, such as and without limitation, titanium, titaniumalloys, aluminum, aluminum alloys, iron, stainless steel, carboncomposites, Inconel, etc., with a preference toward non-conductivematerials. Furthermore, in some embodiments, combinations of metal andcomposite materials may be used, without departing from the scope of thepresent disclosure.

Turning now to FIGS. 5A-5B, schematic illustrations of differentmaterial arrangements for rotor sleeves in accordance with the presentdisclosure are shown. Each of the rotor sleeves 500, 502, 504 shown inFIG. 5A are configured to house a magnet assembly with substantiallyU-shaped magnets and include a hub flange extending therefrom. Each ofrotor sleeves 550, 552, 554 shown in FIG. 5B illustrate differentgeometries and component arrangements of the rotor sleeves with the hubflanges omitted therefrom (although such hub flanges may be incorporatedwith these embodiments).

A first rotor sleeve 500 is formed of a unitary material 506, such asmetal. In this illustrative configuration, the first rotor sleeve 500includes an inner sleeve 508 which may be formed from a differentmaterial, such as carbon fiber composites. Additionally, in thisillustrative configuration, an outer sleeve 510 is provided as abounding sleeve to provide structural support due to the forces andstresses during rotation of the first rotor sleeve 500. The first rotorsleeve 500 also includes a hub flange 512. The hub flange 512 isconfigured to enable attachment to a hub, as shown and described herein,such as by welding or other attachment means.

A second rotor sleeve 502, shown in FIG. 5A, is formed from two separatematerials. In this configuration, the second rotor sleeve 502 includes afirst material portion 514 and a second material portion 516. In anon-limiting embodiment, the first material portion 514 may be formedfrom metal and the second material portion 516 may be formed fromcomposite materials, such as carbon fiber composites havingunidirectional fibers and/or fabrics as reinforcement and resins such asepoxy and polyimide as matrix. Further, in some embodiments, thecomposite materials can include thermoplastic polymers such as PEEK,PPS, polyamide and polyimide. Further, other fibers, such as aramid andglass fibers, may also be used for mitigating corrosion risk betweenmetal and carbon. Light weight titanium, aluminum and magnesium alloysmay be metallic material candidates, for example. In this configuration,the first material portion 514 includes a hub flange 518, formed fromthe same material as the first material portion 514. Also shown in thisconfiguration is an inner sleeve 520 which may be formed from acomposite material, the same or different from the material of thesecond material portion 516. In this embodiment, because the secondmaterial portion 516 is arranged as the outer diameter of the secondrotor sleeve 502, an outer sleeve may be omitted. However, in otherembodiments, an outer sleeve similar to that shown in with respect tothe configuration of the first rotor sleeve 500 may be employed.

A third rotor sleeve 504, shown in FIG. 5A, is formed from two separatematerials. In this configuration, the third rotor sleeve 504 includes afirst material portion 522 and a second material portion 524. In anon-limiting embodiment, the first material portion 522 may be formedfrom metal and the second material portion 524 may be formed fromcomposite materials, such as carbon fiber composites. In thisconfiguration, the first material portion 522 includes a hub flange 526,formed from the same material as the first material portion 522. Alsoshown in this configuration is an inner sleeve 528 which may be formedfrom a composite material, the same or different from the material ofthe second material portion 524. In this embodiment, because the secondmaterial portion 524 is arranged as the outer diameter of the thirdrotor sleeve 504, an outer sleeve may be omitted. However, in otherembodiments, an outer sleeve similar to that shown in with respect tothe configuration of the first rotor sleeve 500 may be employed.

In the configuration of the first rotor sleeve 500, a single material isused to form a substantially U-shaped cross-sectional geometry with aU-shaped channel defined therein. The U-shaped channel is sized andshaped to receive U-shaped magnets as shown and described above. Thesecond material parts (inner sleeve 508 and outer sleeve 510) mayprovide for increased structural support to the ring-shaped or annularstructure of the first rotor sleeve 500. In the configuration of thesecond rotor sleeve 502, two substantially J-shaped pieces (firstmaterial portion 514 and second material portion 516) may be joined toform the second rotor sleeve 502. The joining of the first materialportion 514 to the second material portion 516 may be by, for example,welding, bonding, adhesives, mechanical connection (e.g., brackets,fasteners, and the like), etc., as will be appreciated by those of skillin the art. In the configuration of the third rotor sleeve 504, asubstantially J-shaped first material portion 522 is connected to asubstantially i-shaped or l-shaped second material portion 524.

In FIG. 5B, a fourth rotor sleeve 550 is shown having a substantiallyU-shape and is formed as a continuous material or unitary piece. Assuch, an inner diameter wall 556, a connecting wall 558, and an outerdiameter wall 560 are all formed as a single, continuous piece orstructure. A fifth rotor sleeve 552, shown in FIG. 5B, is formed ofthree separate pieces 562, 564, 566. When the pieces 562, 564, 566 ofthe fifth rotor sleeve 552 are joined together, they will form asubstantially U-shaped rotor sleeve. The joining of the pieces 562, 564,566 may be by welding, bonding, fastener, adhesive, or the like, as willbe appreciated by those of skill in the art. A sixth rotor sleeve 554,shown in FIG. 5B, is formed of three separate pieces 568, 570, 572. Whenthe pieces 568, 570, 572 of the fifth rotor sleeve 554 are joinedtogether, they will form a substantially open box-shaped rotor sleeve.In this embodiment, an inner diameter wall 568, a connecting wall 570,and an outer diameter wall 572 may be joined to form a box-like rotorsleeve. In this configuration, there is no rounded corners, which mayaid in manufacturing, joining, assembly and the like. The sixth rotorsleeve 554 may house a U-shaped magnet, with empty corner present orfilled with a filler or support material or may house a box-shapedmagnet structure that is substantially similar in geometry as the sixthrotor sleeve 554. The joining of the pieces 568, 570, 572 may be bywelding, bonding, fastener, adhesive, or the like, as will beappreciated by those of skill in the art.

It will be appreciated that the configurations in FIGS. 5A-5B are merelyfor example and other arrangements of the material, pieces, and/orcomponents for the rotor sleeve may be employed without departing fromthe scope of the present disclosure.

In each of the embodiments of FIG. 5A, the rotor sleeves 500, 502, 504include a hub flange 512, 518, 526. The hub flange 512, 518, 526 may bedirectly cast, machined, or otherwise formed with the respectiveportions of the rotor sleeves 500, 502, 504. In some embodiments, thehub flange 512, 518, 526 may be manufactured separately from the rotorsleeves and may be affixed by known means, such as welding, bonding, andthe like. It will be appreciated that similar hub flanges may beincorporated onto the rotor sleeves illustratively shown in FIG. 5B.

Turning now to FIG. 6A, a schematic illustration of a sleeve and hubassembly 600 for an aircraft electric motor in accordance with anembodiment of the present disclosure is shown. The sleeve and hubassembly 600 includes a rotor sleeve 602 and a hub 604. The rotor sleeve602 as shown is a single material configuration, although otherconfigurations, as shown and described herein, may be used withoutdeparting from the scope of the present disclosure. The rotor sleeve 602includes a hub flange 606 that extends radially inward from an innerportion of the rotor sleeve 602. The hub flange 606 is configured toreceive the hub 604 and fixedly and securely connect the hub 604 to therotor sleeve 602.

The rotor sleeve 602 defines a U-shaped channel 608 for receiving arotor and stator assembly, as shown and described herein. The rotorsleeve 602 also defines a sleeve inner cavity 610 defined radiallyinward from the U-shaped channel 608, which is an annular structure. Thehub 604 is arranged within the sleeve inner cavity 610 and is configuredto connect the rotor sleeve 602 to a gear assembly that is housed withinthe sleeve inner cavity 610. The hub 604 includes a central bore 612 forreceiving or engaging with a shaft (e.g., a high speed shaft or, forexample, the first shaft 220 shown in FIGS. 2C-2D). In some embodiments,the shaft may be integrally formed with the hub 604. In otherembodiments, the central bore 612 may be provided for engagement withthe shaft, such as by a toothed connection, a threaded connection,welding, bonding, or the like.

FIG. 6A illustrates a solid body hub 604. However, alternativeconfigurations are possible, which may provide for reduced weight, suchas a spoke-style hub 614, as shown in FIG. 6B. The spoke hub 614includes a plurality of spokes 616 extending between an inner element618 and an outer element 620 of the hub 614. In such spoke-typeconfiguration, the inner element 618 may be configured to engage with afirst, input, or high speed shaft of an aircraft electric motor, and theouter element 620 may be configured to engage with a portion of a rotorsleeve, such as the hub flange 606 of the rotor sleeve 602 shown in FIG.6A.

As noted above, in some embodiments of the present disclosure, the rotorsleeve may be formed from metal, composite materials, or combinationsthereof. Similarly, the hub may also be formed from metal, compositematerials, or combinations thereof.

In the above description of the rotor sleeve and hub (FIGS. 4-6 ), aU-shaped rotor sleeve may be employed with an inner sleeve to house andsupport magnets of the rotor of an aircraft electric motor. The rotorsleeve, the inner sleeve, and the hub are configured to rotate togetherat high speed. The torque is transferred through the flange/hub to ashaft of the motor (e.g., first shaft 220 shown in FIGS. 2C-2D). Thefull U-shaped sleeve design, shown in FIG. 4 , configuration 500 of FIG.5 , and FIG. 6 , presents the most integrated design and because of thecompounded curvature, may require highly drapeable composite sheetmaterial such as carbon fiber fabrics and/or braided materials. However,as shown and described, the U-shaped rotor sleeve may be broken downinto two or more parts. For example, in the configuration 502, twohalves may be arranged in a mirrored J-shape. The J-shaped design mayreduce some of the cantilever load from centrifugal forces caused byhigh speed rotation. The inclusion of an inner sleeve (e.g., innersleeve 324 shown in FIG. 3B, or inner sleeves 508, 520, 528 of FIG. 5 ),the inner half J-shaped sleeve may have less structural load and itsweight may be reduced further. Furthermore, the J-shape design can bemore easily constructed using composite materials. Alternatively, inother embodiments, the U-shaped sleeve may be formed into three pieces.In such a configuration, two rings may be joined by a straightsection/plate. That is, with reference again to FIG. 4 , the innerdiameter wall 402, the connecting wall 404, and the outer diameter wall406 may each be separately manufactured and then joined together to formthe rotor sleeve 400.

As described above, the gear assembly may be integrated or embeddedwithin the aircraft electric motor in accordance with embodiments of thepresent disclosure. In accordance with some embodiments of the presentdisclosure, an embedded high power density planetary gearbox provides animproved component of an electric drive train (EDT) for a quiet, safe,reliable and efficient electrified aircraft propulsion (EAP) system. Thegearbox reduces the input speed from the motor to drive a propeller,ensuring a desired combined efficiency of controlling electromagnetic,thermomechanical, and aerodynamic processes.

As noted above, an independent, conventional gearbox increases thesystem weight and size and thus cancels out the intended EAP economicbenefits. In addition, such larger systems may be associated with higherpropeller tip speed and more trapped air, inducing abnormal noise. Inaccordance with embodiments of the present disclosure, a planetarygearbox is embedded into the motor structure and combines bi-material orhybrid gear design and manufacturing and carbon fiber reinforced polymermatrix composite (CF-PMC) structure and connections to maximize systempower density and efficiency. Such embedded gear box may be implementedwithin the sleeve inner cavity of the rotor sleeves described above.

Embodiments described herein provide for improved sleeve and flange/hubarrangements for use in aircraft electric motors. As shown and describedabove, the U-shaped rotor sleeve, along with an internal ring sleeve,can house and support magnets of the rotor and these components canrotate together at high speed. The torque is transferred through theflange/hub to the motor shaft (e.g., first shaft). In accordance withvarious embodiments, full U-shaped sleeve designs, mirrored J-shapedesigns, or other segmented configurations may be employed. Thesegmented configurations (J-shape or otherwise) may reduce some of thecantilever load from centrifugal forces caused by high speed rotation,as compared to a full U-shape configuration, for example.

In accordance with embodiments of the present disclosure, an integratedplanetary gearbox is arranged inside the rotor sleeve with a sun gearoperably connected to an input shaft which is connected to thehigh-speed U-shaped rotor sleeve, such as shown and described above. TheU-shaped rotor sleeve may include a hybrid CF-PMC/titanium structure(e.g., the components of the rotor sleeve, hub, etc.). In accordancewith some embodiments, lightweight gears for the gear assembly can be,for example, hybrid gears made out of high strength material for thetooth rim and the balance made out of symmetric low density, highstrength composite ply layups for the web. In another configuration,such lightweight gears may be bi-metal gears made from a high toughnessand thermal resistance alloy, such as Ferrium C64, and a lightweightalloy. The gear design will be optimized based on the manufacturingoption. The gearbox housing and flange/hub can be made out of CF-PMC toprovide improved specific strength and stiffness and reduce the weightby 30-40% as compared to a conventional gear assembly. A hybridCF-PMC/titanium structure may be used to hold the cantilever rotor andconnect to the gearbox sun gear shaft (first or input shaft). In someembodiments, the gearbox or gear assembly may be jet-sprayed cooled withheat rejected to ram air in a dedicated heat-exchanger. Further, in someembodiments, cooling fluid may be channeled through a cooling systemdescribed above and through part of the gearbox, thus forming aclosed-loop or substantially closed-loop cooling cycle.

Turning now to FIGS. 7A-7E, schematic illustrations of an aircraftelectric motor 700 having a gear assembly 702 in accordance with anembodiment of the present disclosure are shown. FIGS. 7A-7C illustratepartial views of the aircraft electric motor 700 and FIGS. 7D-7Eillustrate the gear assembly 702 in isolation separate from the rest ofthe components of the aircraft electric motor 700.

The aircraft electric motor 700 includes a stator 704, such as shown anddescribed above, and a rotor formed of a rotor sleeve 706 and U-shapedmagnets 708 arranged therein where are arranged within a motor housing710. A hub 712 is fixedly connected to the rotor sleeve 706 at a hubflange 714. The hub 712 is fixedly connected to or integrally formedwith a first shaft 716. The first shaft 716 may be an input shaft thatis rotationally driven by rotation of the rotor sleeve 706 which iscaused to rotate due to electromagnetic interaction between the U-shapedmagnets 708 of the rotor and the stator 704 which may receive electricalcurrent from one or more power module systems, as described above.

The first shaft 716 is fixedly attached to the hub 712, supported onfirst bearings 718, and operably or fixedly connected to a sun gear 720.The first bearings 718 rotationally isolate the first shaft 716 relativeto the motor housing 710 and a second shaft 722. The second shaft 722includes a shaft element 724 and a shaft body 726, described furtherherein. The engagement between the first shaft 716 and the sun gear 720may be by bonding, welding, or other joining process/method or may be amechanical connection, such as through a toothed or slot-grooveconnection, for example.

The sun gear 720 is a toothed component that is configured to engage andoperate with one or more planetary gears 728. The planetary gears 728are mounted to a portion of the motor housing 710. For example, as shownin this embodiment, the planetary gears 728 are mounted and supported ongear shafts 730 that are integral components or parts of the motorhousing 710. As the first shaft 716 is rotationally driven, the sun gear720 will be rotated, which will cause the planetary gears 728 to rotaterelative to a ring gear 732. The ring gear 732 is fixedly or operablyconnected to the shaft body 726 of the second shaft 722. As such, as thering gear 732 is caused to rotate by interaction with the planetarygears 728, the shaft body 726 will be rotated, which in turn causes theshaft element 724 of the second shaft 722. The second shaft 722 may bean output shaft that is operably connected to a fan shaft or othercomponent to impart rotationally movement thereto. The shaft element 724of the second shaft 722 may be rotationally supported on second bearings734.

As illustratively shown, the gear assembly 702 is arranged as aconcentric or substantially planar assembly providing for a low profileor compact configuration such that the entire gear assembly 702 issubstantially housed within the motor housing 710. Further, as shown,the gear assembly 702 is arranged within the sleeve inner cavity of therotor sleeve 706. As such, a very compact electric motor for an aircraftmay be achieved through the gear assembly configuration of the presentdisclosure. The gear assemblies of the present disclosure can provideimproved power density, increased efficiency, noise reduction, robustperformance, and improved reliability as compared to prior gear assemblysystems.

In accordance with some embodiments, high power density gears may beincorporated. In some embodiments, hybrid gears made out of or formedfrom high strength material for the tooth rim and the balance or rest ofthe gear structure may be formed out of symmetric low density, highstrength composites. Such symmetric low density, high strengthcomposites may include, without limitation, carbon fiber reinforcedpolymer matrix composite ply layups for the web. In such configurations,using advanced composite material(s) in hybrid gears can lighten theweight of the gear assembly (and motor) while ensuring the level oftorque transfer compared to an all-metallic gearing configuration. Inother embodiments, high power density gears may be formed using amodel-based design of bi-metal gears made from a high toughness andthermal resistance alloy(s), such as, but not limited to, Ferrium C64and a lightweight alloy. In these configurations, weight reduction maybe provided from the introduction of a lightweight gear web throughtopology optimization and possible additive manufacturing.

As shown and discussed above, the components of the aircraft electricmotors are housed, at least partially, within a motor housing. FIG. 8 isa schematic illustration of a motor housing 800 in accordance with anembodiment of the present disclosure. The motor housing 800, in someembodiments, may be a single, unitary body that is machined, cast,molded, or otherwise manufactured as a single component of a singlematerial. The motor housing 800 includes an outer wall 802 and an innerwall 804. The motor housing 800 is circular in shape and the inner wall804 is arranged radially inward from the outer wall 802. A rotor-statorcavity 806 is defined between the outer wall 802 and the inner wall 804.The outer wall 802 may be connected to the inner wall 804 by a pluralityof connectors 808. The connectors 808 define access apertures 810between circumferentially adjacent connectors 808. The access apertures810 are configured to enable electrical and cooling connections frompower systems and/or cooling systems a stator arranged within therotor-stator cavity 806. The diameter of the inner wall 804 is sized tofit within a sleeve inner cavity of a rotor sleeve and the diameter ofthe outer wall 802 is sized to receive the rotor sleeve between theinner wall 804 and the outer wall 802.

The inner wall 804 defines a gear assembly cavity 812. The gear assemblycavity 812 is configured to receive a gear assembly of the aircraftelectric motor. The motor housing 800 includes a shaft aperture 814 forreceiving, for example, a first shaft or input shaft of the aircraftelectric motor. The motor housing 800 also includes gear shafts 816 thatare configured to receive gears of the gear assembly (e.g., planetarygears). As shown, in this configuration, access to the rotor-statorcavity 806 and the gear assembly cavity 812 are from opposite sides ofthe motor housing 800. This directional configuration can aid inarrangement and engagement of components of the aircraft electric motor,as shown and described above.

Referring to FIG. 9 , a power system 900 of an aircraft 902 is shown.The power system 900 includes one or more engines 904, one or moreelectric motors 906, a power bus electrically connecting the variouspower sources 904, 906, and a plurality of electrical devices 910 thatmay be powered by the engines 904 and/or motors 906. The power system900 includes a power distribution system 912 that distributes power 914through power lines or cables 916. The electric motors 906 be configuredas the aircraft electric motors shown and described above.

Advantageously, embodiments of the present disclosure provide forimproved electric motors for aircraft and aviation applications. Theaircraft electric motors of the present disclosure may include ahigh-speed (e.g., 15000 RPM) rotor with U-shaped high-strength magnets.This configuration enables maximization of the coil and magnetutilization, therefore maximizing torque density. The gear assemblies ofthe present disclosure are integrated inside the rotor structure alongwith bearings on both high-speed (e.g., first or input) and low-speed(e.g., second or output) shafts. In some embodiments, distributed driveis arranged in close proximity to the motor winding terminal. Further,in accordance with some embodiments, Litz wires may be wound aroundstacked ring laminations that incorporate embedded cooling channelsalongside the motor windings. Such windings may be supported by ceramicstator teeth with additional embedded channels. Additionally, in someembodiments, an integrated flow header, located between the motor anddrive, can provide thermal management to the system.

As described herein, embodiments of the present disclosure may providefor light-weight components. The light-weight materials, describedabove, can be used to form the specifically described components of themotor and/or other parts/components of the motors described herein. Itwill be appreciated that composite materials of the present disclosurecan include, without limitation, composite with woven fabric, compositewith braided fabric, composite with carbon fiber, composite with glassfiber, composite aramid fiber, composite with multiple type of fibers,composite with short fibers, and/or composite with continuous fibers.Such composite materials may be incorporated into system that also usemetals which may include, without limitation, titanium, titanium alloys,aluminum, aluminum alloys, iron, stainless steel, Inconel. It will beappreciated that other metals and/or composite materials may be employedwithout departing from the scope of the present disclosure.

The terms “about” and “substantially” are intended to include the degreeof error associated with measurement of the particular quantity basedupon the equipment available at the time of filing the application. Forexample, “about” or “substantially” can include a range of ±8% or 5%, or2% of a given value.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,element components, and/or groups thereof.

While the present disclosure has been described with reference to anexemplary embodiment or embodiments, it will be understood by thoseskilled in the art that various changes may be made and equivalents maybe substituted for elements thereof without departing from the scope ofthe present disclosure. In addition, many modifications may be made toadapt a particular situation or material to the teachings of the presentdisclosure without departing from the essential scope thereof.Therefore, it is intended that the present disclosure not be limited tothe particular embodiment disclosed as the best mode contemplated forcarrying out this present disclosure, but that the present disclosurewill include all embodiments falling within the scope of the claims.

What is claimed is:
 1. An aircraft electric motor comprising: an annularrotor sleeve having an inner wall, a connecting wall, and an outer wall,wherein the inner wall, the connecting wall, and the outer wall define aU-shaped channel configured to receive a U-shaped magnet structure and asleeve inner cavity defined radially inward from the inner wall, with anopen end of the U-shaped channel defined between the inner wall and theouter wall and opposite the connecting wall; a hub connector extendingradially inward from the inner wall into the sleeve inner cavity; a hubarranged in the sleeve inner cavity and fixedly connected to the hubconnector, wherein the hub is configured to rotate with rotation of therotor sleeve; and a U-shaped magnet structure arranged within theU-shaped channel of the rotor sleeve, wherein the U-shaped magnetstructure comprises a set of alternating polarity U-shaped magnets eachhaving an open end and a closed end opposite the open end, and eachU-shaped magnet is configured to receive at least one winding within aninterior of the U-shaped magnet, wherein at least one of the rotorsleeve, the hub connector, and the hub are formed from a compositematerial.
 2. The aircraft electric motor of claim 1, wherein the hubcomprises a plurality of spokes extending between an inner element andan outer element of the hub.
 3. The aircraft electric motor of claim 1,further comprising an outer sleeve arranged about an exterior of theouter wall of the rotor sleeve.
 4. The aircraft electric motor of claim1, further comprising a cooling system having a heat exchanger arrangedradially outward from the outer wall of the rotor sleeve.
 5. Theaircraft electric motor of claim 1, wherein the composite material is atleast one carbon fiber fabric, carbon fiber composite, and braidedmaterial.
 6. The aircraft electric motor of claim 1, wherein the rotorsleeve is formed of two pieces that are joined together, wherein eachpiece of the rotor sleeve is substantially J-shaped.
 7. The aircraftelectric motor of claim 1, wherein the rotor sleeve is formed of twopieces that are joined together, wherein one piece of the rotor sleeveis substantially J-shaped and the other piece of the rotor sleeve issubstantially 1-shaped.
 8. The aircraft electric motor of claim 1,wherein the rotor sleeve is formed of two pieces that are joinedtogether, wherein one piece of the rotor sleeve is formed from metal andthe other piece of the rotor sleeve is formed from the compositematerial.
 9. The aircraft electric motor of claim 1, further comprisingan inner sleeve arranged within the U-shaped channel and configured toprovide support to the U-shaped magnet structure.
 10. The aircraftelectric motor of claim 1, further comprising a stator arranged withinthe U-shaped magnet structure.
 11. The aircraft electric motor of claim1, further comprising an input shaft connected to the hub.
 12. Theaircraft electric motor of claim 1, further comprising a gear assemblyarranged within the sleeve inner cavity.
 13. The aircraft electric motorof claim 12, wherein the rotor sleeve is operably connected to the gearassembly by the hub.
 14. The aircraft electric motor of claim 12,wherein the gear assembly comprises a sun gear, one or more planetarygears, and a ring gear.
 15. The aircraft electric motor of claim 14,wherein an input shaft connects the hub to the sun gear and an outputshaft is operably connected to the ring gear.
 16. The aircraft electricmotor of claim 1, further comprising a motor housing, wherein the rotorsleeve is arranged within the motor housing.
 17. The aircraft electricmotor of claim 16, wherein the motor housing is substantially annular inshape, having an outer wall and an inner wall, wherein a rotor-statorcavity is defined between the outer wall and the inner wall, and therotor sleeve is arranged within the rotor-stator cavity.
 18. Theaircraft electric motor of claim 16, wherein the motor housing issubstantially annular in shape, having an outer wall and an inner wall,wherein a gear assembly cavity is defined radially inward from the innerwall, and a gear assembly is arranged within the gear assembly cavity.19. The aircraft electric motor of claim 18, wherein the motor housingincludes gear shafts within the gear assembly cavity, the gear shaftsconfigured to support gears of the gear assembly.
 20. The aircraftelectric motor of claim 1, wherein the hub comprises a plurality ofspokes extending between an inner element and an outer element of thehub.
 21. An aircraft electric motor comprising: an annular rotor sleevehaving an inner wall, a connecting wall, and an outer wall, wherein theinner wall, the connecting wall, and the outer wall define a U-shapedchannel configured to receive a U-shaped magnet structure and a sleeveinner cavity defined radially inward from the inner wall; a hubconnector extending radially inward from the inner wall into the sleeveinner cavity; a hub arranged in the sleeve inner cavity and fixedlyconnected to the hub connector, wherein the hub is configured to rotatewith rotation of the rotor sleeve; a U-shaped magnet structure arrangedwithin the U-shaped channel of the rotor sleeve; and a gear assemblyarranged within the sleeve inner cavity, wherein at least one of therotor sleeve, the hub connector, and the hub are formed from a compositematerial.